1 files changed, 7 insertions, 6 deletions

diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index b4929b445..6409874ff 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -7,6 +7,7 @@
 #include "topo-sort.hh"
 #include "callback.hh"
 #include "closure.hh"
+#include "filetransfer.hh"
 
 namespace nix {
 
@@ -100,7 +101,8 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
 
     downloadSize_ = narSize_ = 0;
 
-    ThreadPool pool;
+    // FIXME: make async.
+    ThreadPool pool(fileTransferSettings.httpConnections);
 
     struct State
     {
@@ -166,7 +168,7 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
         }
 
         std::visit(overloaded {
-          [&](DerivedPath::Built bfd) {
+          [&](const DerivedPath::Built & bfd) {
             if (!isValidPath(bfd.drvPath)) {
                 // FIXME: we could try to substitute the derivation.
                 auto state(state_.lock());
@@ -199,7 +201,7 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
                 mustBuildDrv(bfd.drvPath, *drv);
 
           },
-          [&](DerivedPath::Opaque bo) {
+          [&](const DerivedPath::Opaque & bo) {
 
             if (isValidPath(bo.path)) return;
 
@@ -239,12 +241,11 @@ StorePaths Store::topoSortPaths(const StorePathSet & paths)
 {
     return topoSort(paths,
         {[&](const StorePath & path) {
-            StorePathSet references;
             try {
-                references = queryPathInfo(path)->references;
+                return queryPathInfo(path)->references;
             } catch (InvalidPath &) {
+                return StorePathSet();
             }
-            return references;
         }},
         {[&](const StorePath & path, const StorePath & parent) {
             return BuildError(